Theory and troubleshooting using short modules packed with images to make learning quick and easy.
There are two types of capacitors you'll encounter in HVAC field. We have the run capacitor and the start capacitor. Both are measured in microfarads which you will see labeled as uf, µF, or mfd. Capacitors are used only in single-phase motors. You will not see a capacitor in a three-phase unit. Run Capacitor Max…
The potential relay is used in all capacitor start/capacitor run motors. They're also used in capacitor start/induction run motors. However, it's rare to see that style of a motor in residential and lite commercial in our industry. The potential relay may also be called a start relay. Without it, the start capacitor could explode or…
Relay We’ll be using the most common type of relay in residential service, a 24v relay. A relay is an electronically operated switch that opens and closes using an electromagnet. The electromagnet is a coil of wire that when powered acts as a magnet to close/open a switch. The above image has two banks of…
A switch opens and closes to allow the flow of electric current or to stop it. There are many types of switches including, but not limited to manual switch you would have to turn on an off, switches reacting to pressure, heat, or to water or air. Switches are designed to be either normally open…
Position diagram The position diagram shows the location of all components and is most often not included by the manufacturer. Schematic Diagram Schematic diagrams are also known as ladder diagrams and are helpful when you need to see the electrical current flow. Schematics will not show the physical location of any equipment in the circuit.…
Wiring diagrams are used as a map to find your way through the electrical circuit. Schematic and Connection diagrams (also known as wiring diagram) are the two main types of wiring diagrams. Using the schematic diagram, you can learn the sequence of operation if it's an appliance you're not sure of. The connection diagram (also…
The flame sensor exists to prove a flame across the burners. Without this flame sensor, there’s a risk of releasing gas without flame and risking an explosion upon ignition. The flame sensor is positioned on the opposite end of the burners from the igniter to ensure all burners ignite correctly. Upon a call for heat,…
When passing an alternating current through a coil of wire, like a transformer or a solenoid valve, the expanding and collapsing magnetic field created by the alternating current induces a back-voltage (back EMF) in the coil which goes against the supply voltage. All coils of wire will have this. If you have two sets of…
Solenoids operate on the principle of electromagnetism. With current moving through a conductor, a magnetic field forms around the conductor. A single straight conductor by itself will not generate a strong magnetic field, but if the conductor is wound into a tight coil, it will produce a strong magnetic field. Each loop of the coil…
A GFCI is not the same as a breaker or fuse. It exists to protect people whereas a fuse or breaker exists to protect the conductors in your house. A GFCI works on the principle that the current moving through a circuit should be the same at all points of the circuit. The GFIC monitors…